The invention relates to a print engine/controller (PEC) suitable for use with a range of printer products. The invention further relates to a print engine/controller implemented in a print head interface chip.
A range of printer types have evolved wherein an image is constructed from ink selectively applied to a page in dot format. In U.S. Pat. No. 6,045,710 titled xe2x80x98Self-aligned construction and manufacturing process for monolithic print headsxe2x80x99 to the inventor Kia Silverbrook there is set out an assessment of the prior art to drop on demand printers along with its manufacturing process.
A microelectomechanical drop on demand print head hereafter referred to as a Memjet pint head has been described in co-pending United States Patent Applications filed simultaneously to the present application and hereby incorporated by cross reference:
The Memjet print head is developed from print head segments that are capable of producing, for example, 1600 dpi bi-level dots of liquid ink across the full width of a page. Dots are easily produced in isolation, allowing dispersed-dot dithering to be exploited to its fullest. Color planes might be printed in perfect registration, allowing ideal dot-on-dot printing. The print head enables high-speed printing using microelectomechanical ink drop technology.
Various methods, systems, and apparatus relating to a printed page based communications network that is best worked with high-speed page printing has been disclosed in co-pending United States Patent Applications/granted patents filed simultaneously by the applicant or assignee of the present invention and are hereby incorporated by cross reference:
The disclosures of these co-pending applications are incorporated herein by cross-reference.
Performance of a print head such as the above is dictated by its engine/controller. High-speed printing is a matter of development of both the print head and its engine/controller. A page wide print head enabled by the above technology needs an engine/controller capable of feeding it high rates of drop control signals. A typical page layout may contain a mixture of images, graphics and text. Because of the page-width nature of the above microelectomechanical print head, each page can be printed at a constant speed to avoid creating visible artifacts. This means that the printing speed need not be varied to match the input data rate. Document rasterization and document printing can be decoupled. To ensure the print head has a constant supply of data, a page should not be printed until it is fully rasterized. Ideally rasterization should be able to run ahead of the printer when rasterizing simple pages, buying time to rasterize more complex pages. The engine/controller determines the degree to which these functions might be realised.
More speed at the print head depends on development of both print head and its engine/controller. The print engine/controller architecture needs to be designed to push large volumes of data to the print head at high speed.
In one form the invention resides in a print engine/controller comprising:
a contone image decoder;
a bi-level compression decoder; and
a half-toner/compositor and print head interface.
The print engine/controller provides the final steps for producing a page from compressed page data appropriately formatted for it by a computer or print distribution system, the steps being: expanding the page image, dithering the contone layer, compositing the black layer over the contone layer, adding infrared tags to the infrared layer, and sending the resultant image to the print head.
The print engine/controller preferably uses a high speed serial interface at which to receive compressed page data. Contone image planes are decoded by a JPEG decoder and they are scaled in the halftoner/compositor under control of a margin unit. A Group 4 facsimile decoder decodes the bi-level image plane and it also is scaled in the halftoner/compositor under control of the margin unit. Optionally an infrared tag encoder serves to produce an infrared image plane to place infrared ink printed tags into a printed page. The halftoner/compositor includes a dither matrix access unit to supply dither data from the compressed page data by which to dither the contone image plane.
The invention further includes a print engine/controller chip to interface with an ink drop print head comprising an interface at which to receive compressed page data, a contone image decoder to decode any continuous tone image planes in the received compressed page data, a bi-level decoder to decode any bi-level image planes and dither data in the received compressed page data, a half-toner/compositor to composite any bi-level image plane over any continuous tone image plane, and a print head driver to output the composite to a print head.